What is the best cruising RPM ?? I need a good rear ratio and tranny! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

smoknbarrels · 02-06-2007, 11:06 PM

Hi, I have some problems with tranny and rear selection..
I have been trying to cut corners and determine a tranny that will hold up to my moderate perf 454, it has lots of cam and I will be going with a standard tranny..
I have been looking at Tremec 6 speeds, all the gears are great ratios until the 6th.. it is 0.50. so with my 29 inch tall tires I will only be doing 1500 RPM at 65 MPH. This is far to low isn't it?? I know corvettes run at 1300 RPM on the hiway(same tranny), but this can't be done with my carburated engine can it? people say I need my engine at a minimium of 2000 RPM.

I really would like an overdrive but I don't know of any other popular affordable Trannys that will hold up to 500lbs of torque..? muncies are great, but they lack an over drive, I don't want to drive down the hiway doing 3300 RPM.
I wanted a Tremec TKO-600 but they are too much (would have been perfect).

Have any ideas!??

cooters · 02-06-2007, 11:12 PM

i dont know what you have for a motor combo, a 454 with an rv style cam would be awesome at 2000rpm.

smoknbarrels · 02-07-2007, 12:41 AM

My 454 has ported heads, intake, headers, with a few other goodies, but the big thing affecting my RPM would be my cam , which is 292 adv. duration and 550 valve lift. so it is much larger then an RV cam. its power band is about 2500-6500 RPM.
I don't nessisarily think that I need to be cruising in that range do I?

would it run good under 2000 RPM on the hiway? perhaps someone has tried this before...

RACINJASON22 · 02-07-2007, 01:00 AM

here are some #'s for ya. Hope they will help. I'm not real sure about the bigblock stuff cam seems a little big just the #'s
Ratio = (rpm x tire diameter) divided by (mph x 336)

RPM = (mph x gear ratio x 336) divided by (tire diameter)

MPH = (rpm x tire diameter) divided by (gear ratio x 336)

Tire Diameter = (mph x gear ratio x 336) divided by (rpm)

smoknbarrels · 02-07-2007, 01:41 AM

yea, i have been using some good online calculators, but I just don't know what would be a good RPM to run my big block with on the hiway..?
Does anyone know of a good strong manual tranny that has good ratios?

I can get my hands on a cheap Borg Warner super T-10, if I have to go to a 4 speed (is it as strong as a muncie?) but then I also go to a 3.08 ratio rear end.

cooters · 02-07-2007, 09:49 AM

you should be in the power range while cruising. Depending what you are doing, a new process 4500 is ok, or a T5

71Chevy4-speed · 02-07-2007, 10:53 AM

http://www.richmondgear.com/01sixspeed.html

5th is 1:1
6th is overdrive.

smoknbarrels · 02-07-2007, 01:30 PM

that looks good, you can even pick all your ratios.. also looks expensive.. i think i looked at these richmond 6 gears before.. but they were in the $3000 range.. which is unfortunately a little out of my range. since they are not common i would have to buy it new..
I have been looking at the T-56 that LS-1's use.. its a 6 speed.. all gears are good but 6th is too low of ratio, so I was thinking of just only driving with 5 gears. since those trannys are popular and cheap.

perhaps call 6th gear a "police interceptor passing gear" since I would be doing 230 MPH @ 5000 RPM with my set up. LOL..! sounds like a waste thou.

Longhorn Man · 02-07-2007, 03:52 PM

a T 5 can't hold up to a strong 305, there's a reason GM never bolted them to a 350... ever.
Are you racing your big block, or just want a kick ass strong motor?
You should have enough torque to not need real deep gears. A normal old 4 speed stick, or a Th400 if you are sick of shifting, would be idea with a 3.07 gear. You'll cruise at 2500 or so.

1968SWBBigBlock · 02-07-2007, 04:12 PM

Hey longhorn - are you on 315 doing 90mph? That could be to slow

Longhorn Man · 02-07-2007, 05:07 PM

west side on I 270 north bound, had it at 100 for a mile or so, had to lift for the exit to I 70 west.

I can't remember where the first photo was taken, that's when the old GMC rolled 500,000 miles.

67ChevyRedneck · 02-07-2007, 05:56 PM

If you really want OD, why not a tremec 5 speed and a 3.73 rear end? That should give you what you want, right?

smoknbarrels · 02-07-2007, 06:12 PM

I will be running about 470 HP in my 454 (Flywheel HP) so i have been trying to find a decent manual tranny that will hold. I also want to determine what RPM is good to cruise at, (being I have lots of cam).

sounds crazy but i am trying to get the best of both worlds, I want it to be a tough street machine, but also have an over drive gear so it will see pleanty of use on the hiway.

Longhorn Man · 02-07-2007, 07:05 PM

If I'm not mistaken, the tremec 5 speed is not an overdrive.
2000 - 2500 RPM is what I would say you should shoot for.
Any idea on what kinda torque numbers this engine will pull? If it has a bunch of torque down low, then a low gear would be wasted. The caddy motors make so much low end power that you can run real low gears, like a high 2.something, and it'll still pull like crazy from the lights, yes loaf along at 2000 RPM in a one to one final gear. With a tall gear, there is no need for an overdrive, and you indicated cost being an issue... there are no low cost overdrives that'll handle your engine... not for a long peroid of time anyways.

02-06-2007, 11:06 PM	#1
smoknbarrels Registered Mail Join Date: Jun 2006 Location: Alberta, Canada Posts: 513	What is the best cruising RPM ?? I need a good rear ratio and tranny! Hi, I have some problems with tranny and rear selection.. I have been trying to cut corners and determine a tranny that will hold up to my moderate perf 454, it has lots of cam and I will be going with a standard tranny.. I have been looking at Tremec 6 speeds, all the gears are great ratios until the 6th.. it is 0.50. so with my 29 inch tall tires I will only be doing 1500 RPM at 65 MPH. This is far to low isn't it?? I know corvettes run at 1300 RPM on the hiway(same tranny), but this can't be done with my carburated engine can it? people say I need my engine at a minimium of 2000 RPM. I really would like an overdrive but I don't know of any other popular affordable Trannys that will hold up to 500lbs of torque..? muncies are great, but they lack an over drive, I don't want to drive down the hiway doing 3300 RPM. I wanted a Tremec TKO-600 but they are too much (would have been perfect). Have any ideas!?? __________________ '67 chev 496, lwb to swb, bagged - pro street project

02-06-2007, 11:12 PM	#2
cooters Senior Member Join Date: Oct 2006 Location: Edmonton Alberta Posts: 458	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! i dont know what you have for a motor combo, a 454 with an rv style cam would be awesome at 2000rpm.

02-07-2007, 12:41 AM	#3
smoknbarrels Registered Mail Join Date: Jun 2006 Location: Alberta, Canada Posts: 513	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! My 454 has ported heads, intake, headers, with a few other goodies, but the big thing affecting my RPM would be my cam , which is 292 adv. duration and 550 valve lift. so it is much larger then an RV cam. its power band is about 2500-6500 RPM. I don't nessisarily think that I need to be cruising in that range do I? would it run good under 2000 RPM on the hiway? perhaps someone has tried this before... __________________ '67 chev 496, lwb to swb, bagged - pro street project

02-07-2007, 01:00 AM	#4
RACINJASON22 GEARHEAD Join Date: Jan 2007 Location: CENTRAL,PA Posts: 2,284	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! here are some #'s for ya. Hope they will help. I'm not real sure about the bigblock stuff cam seems a little big just the #'s Ratio = (rpm x tire diameter) divided by (mph x 336) RPM = (mph x gear ratio x 336) divided by (tire diameter) MPH = (rpm x tire diameter) divided by (gear ratio x 336) Tire Diameter = (mph x gear ratio x 336) divided by (rpm) __________________ 72 SWB 2WD MY PROJECT 72 LWB 4X4 FUTURE PROJECT SUBSCRIBE HEREBOARD VENDORS HERE NORWOOD MEET SURVIVOR!

02-07-2007, 01:41 AM	#5
smoknbarrels Registered Mail Join Date: Jun 2006 Location: Alberta, Canada Posts: 513	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! yea, i have been using some good online calculators, but I just don't know what would be a good RPM to run my big block with on the hiway..? Does anyone know of a good strong manual tranny that has good ratios? I can get my hands on a cheap Borg Warner super T-10, if I have to go to a 4 speed (is it as strong as a muncie?) but then I also go to a 3.08 ratio rear end. __________________ '67 chev 496, lwb to swb, bagged - pro street project

02-07-2007, 09:49 AM	#6
cooters Senior Member Join Date: Oct 2006 Location: Edmonton Alberta Posts: 458	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! you should be in the power range while cruising. Depending what you are doing, a new process 4500 is ok, or a T5

02-07-2007, 10:53 AM	#7
71Chevy4-speed Speed Limit = Floorboard Join Date: Jan 2004 Location: Kasilof, Alaska Posts: 803	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! http://www.richmondgear.com/01sixspeed.html 5th is 1:1 6th is overdrive. __________________ 1971 C20 350, 4-speed - Sold. 1985 K10 350, Built 700r4, Edel 1406, Performer intake, MSD Ign, Hooker Comps, Silverstars, Piaa drivers, LED tails, Toyo A/T 31's, Eaton Posi, the project. "Build for torque, horsepower will follow"

02-07-2007, 01:30 PM	#8
smoknbarrels Registered Mail Join Date: Jun 2006 Location: Alberta, Canada Posts: 513	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! that looks good, you can even pick all your ratios.. also looks expensive.. i think i looked at these richmond 6 gears before.. but they were in the $3000 range.. which is unfortunately a little out of my range. since they are not common i would have to buy it new.. I have been looking at the T-56 that LS-1's use.. its a 6 speed.. all gears are good but 6th is too low of ratio, so I was thinking of just only driving with 5 gears. since those trannys are popular and cheap. perhaps call 6th gear a "police interceptor passing gear" since I would be doing 230 MPH @ 5000 RPM with my set up. LOL..! sounds like a waste thou. __________________ '67 chev 496, lwb to swb, bagged - pro street project

02-07-2007, 03:52 PM	#9
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! a T 5 can't hold up to a strong 305, there's a reason GM never bolted them to a 350... ever. Are you racing your big block, or just want a kick ass strong motor? You should have enough torque to not need real deep gears. A normal old 4 speed stick, or a Th400 if you are sick of shifting, would be idea with a 3.07 gear. You'll cruise at 2500 or so.

02-07-2007, 04:12 PM	#10
1968SWBBigBlock Active Member Join Date: Oct 2006 Location: Ohio Posts: 1,643	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! Hey longhorn - are you on 315 doing 90mph? That could be to slow __________________ 1968 SWB 454 + .040, 490HP x 540 FT pounds of Torque 10-1 Kb Forged pistons, recon rods w/ ARP wave loc bolts 781 heads Ported with 2.19/1.88 SSTvalves Lunati 60204 cam, Micro Trol lifters, Ported Edelbrock Performer Rpm manifold armor coated, Pertronix Triple Strike Ignition Holley 770 Street Avenger carb,Headers armor coated Built by Watson Ruppel Performance in Sarahsville Ohio. Hardshift Tranny Built Turbo 350,TSI 10" 3000 stall 12 Bolt Eaton Posi 4.10 Richmond Gears moser axles 18.5" x 31" Hoosier Pro Street Radials ET Classic 5 Wheels - polished Power Steering, Power Brakes,Disc Brakes,Tach & Gauge Dash, Tilt,Factory Air (gone) Custom Paint & Body Work Special thanks to my wife, my son and my money tree

02-07-2007, 05:07 PM	#11
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! west side on I 270 north bound, had it at 100 for a mile or so, had to lift for the exit to I 70 west. I can't remember where the first photo was taken, that's when the old GMC rolled 500,000 miles. Last edited by Longhorn Man; 02-07-2007 at 05:07 PM.

02-07-2007, 05:56 PM	#12
67ChevyRedneck Hittin E-Z Street on Mud Tires Join Date: Nov 2004 Location: Greenville, SC Posts: 23,090	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! If you really want OD, why not a tremec 5 speed and a 3.73 rear end? That should give you what you want, right? __________________ Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride American Born, Country by the Grace of God 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications!

02-07-2007, 06:12 PM	#13
smoknbarrels Registered Mail Join Date: Jun 2006 Location: Alberta, Canada Posts: 513	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! I will be running about 470 HP in my 454 (Flywheel HP) so i have been trying to find a decent manual tranny that will hold. I also want to determine what RPM is good to cruise at, (being I have lots of cam). sounds crazy but i am trying to get the best of both worlds, I want it to be a tough street machine, but also have an over drive gear so it will see pleanty of use on the hiway. __________________ '67 chev 496, lwb to swb, bagged - pro street project

02-07-2007, 07:05 PM	#14
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: What is the best cruising RPM ?? I need a good rear ratio and tranny! If I'm not mistaken, the tremec 5 speed is not an overdrive. 2000 - 2500 RPM is what I would say you should shoot for. Any idea on what kinda torque numbers this engine will pull? If it has a bunch of torque down low, then a low gear would be wasted. The caddy motors make so much low end power that you can run real low gears, like a high 2.something, and it'll still pull like crazy from the lights, yes loaf along at 2000 RPM in a one to one final gear. With a tall gear, there is no need for an overdrive, and you indicated cost being an issue... there are no low cost overdrives that'll handle your engine... not for a long peroid of time anyways.



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